May 22, 2017

Images: The Sound of Sonar and the Fury about Whale Strandings

In March 2000, 17 marine mammals, mostly beaked whales, were found stranded on three islands in the North Bahamas following naval exercises involving sonar. (Photo by Nan Hauser, The Center for Cetacean Research & Conservation)

To study beaked whales, researchers used a hydrophone array arranged at 2,000 meters depth in an ocean canyon called the Tongue of the Ocean, off Andros Island in the Bahamas. The array is operated by the U.S. Navy's Atlantic Undersea Test and Evaluation Center (AUTEC) and is traditionally used for weapons testing. (Map courtesy of Google )

To explore links between sonar and marine mammal strandings, the U.S. Navy has offered scientists the use of its extensive Atlantic Undersea Test and Evaluation Center?an interconnected seafloor system of 81 hydrophones (underwater microphones) arranged in the above grid over 600 square nautical miles southeast of Andros Island in the Bahamas. (Courtesy of the Naval UnderseaWarfare Center Marine Mammal Monitoring on Naval Ranges Program)

Biologist Leigh Hickmott with the Bahamas Marine Mammal Research Organization used a carbon-fiber pole to attach a digital tag, or D-tag, with a suction cup to a beaked whale. The tag helps record the whales' behavior, as well as sounds in their environment. Driving the boat is Alessandro Bocconcelli, an engineer (and licensed captain) in the Applied Ocean Physics & Engineering Department at WHOI. (Photo courtesy of the Bahamas Marine Mammal Research Organization)

After this beaked whale was tagged, the device recorded and stored data about the animal's behavior and information about the surrounding ocean environment. Beyond time, depths, and sounds, the tag records temperatures in the ocean surrounding the whale, and the whale?s pitch, roll, speed, and direction. It records sound 192,000 times per second and other information 50 times a second. After 18 hours, the tag automatically pops off the whales and floats to the surface for the researchers to collect. (Photo by Ari Friedlaender, Duke University)

Days with glassy seas were ideal for locating and following beaked whales using the Navy vessel Ranger. (Choppy waters made it difficult to see the whales). This photo was taken from a smaller boat used for tagging the whales. (Photo by Ari Friedlaender, Duke University)

The "Big Eye" binoculars mounted near the bow of the Navy vessel Ranger gave biologist Federico Pongiglione a way to track beaked whales, even from a mile away. (Photo courtesy of Behavioral Response Study)

Darlene Ketten, a biologist at Woods Hole Oceanographic Institution, necropsied the stranded whales in the Bahamas in 2000. (Photo by Nan Hauser, The Center for Cetacean Research & Conservation)

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